Liquid and fluid products of the type mentioned above are packaged conventionally by bottling in containers of which the structure can be fabricated employing a multi-layer or treated paper material, for example cardboard or paperboard coated with one or more layers of food-safe material suitable for liquids.
Containers of the type in question are fashioned generally from flat diecut blanks, detached generally from a roll and then folded suitably along precreased lines in such a way as to form recipients capable of holding the liquid product.
It is standard practice for a communicating duct embodied typically as a tubular element to be applied to the top of each container, providing a spout from which to pour the product; the end of the tubular element farthest from the container can be closed by means of a suitable cap.
The communicating duct is secured to the structure of the respective container by means of a weld, such as will unite the topmost edges of the container structure with a cylindrical portion of the tubular element constituting the duct.
To ensure the communicating ducts are correctly positioned on the respective containers, each duct is furnished with an annular projection serving to delimit the weldable surface of the tubular element uppermost, and affording a stop against which the top edge of the container structure is caused to locate.
Still with reference to the positioning of the communicating ducts on the structures of the relative containers, each communicating duct is furnished generally with one or more projections positioned to locate between joined areas of the container in such a way that each projection will be united with the selfsame joined areas in the course of the welding operation.
Moreover, the welding operations in question typically involve the application of heat, and in order to offset any contraction of the material used to fashion the communicating duct, the longitudinal dimension presented by the tubular element of the duct is greater than the effective longitudinal dimension of the weldable surface, projecting internally of and toward the bottom of the container.
Whilst the communicating ducts thus described afford a protected passage to the food product, it has been found nonetheless that they are not free of drawbacks and might be improved from certain standpoints, as concerning principally the chemical and organoleptic preservation of the bottled food product, the fluid-tightness of the welded areas by which the communicating ducts and the respective containers are united, and the simplicity of the welding operations.
More exactly, it has been found that an excessive oversizing of the tubular element, intended to offset the contraction of the material during the welding operation, results in the formation of hollow retention pockets between the walls of the container and the innermost end of the spout afforded by the tubular element. These pockets are particularly disadvantageous in that they complicate the process of cleaning the inside of the containers after the welding operation, as well as degrading the operation of disposal when the containers are no longer of use. During the washing process, in effect, which is conducted generally with the container sealed and using a special flushing liquid, it happens that a part of the liquid will collect in the aforementioned pockets when the container is emptied. Naturally enough, the presence of the flushing liquid inside the container implies that the food product batched subsequently into the selfsame container will become tainted. Accordingly, the manufacturer is forced to make use of devices designed especially to remove the residual cleansing liquid. This obviously dictates an increase in the costs of producing, and subsequently of marketing the end product.
As regards disposal of the containers on the other hand, the pockets tend undesirably to trap a part of the liquid product used by the consumer, which can then escape accidentally both when the container is placed in the refuse collection bin, and during the operations of crushing and compacting thereafter.
Moreover, the structure of prior art communicating ducts as described above does nothing to facilitate the welding process, given that one or more gaps can form subsequently between the external cylindrical surface of the tubular element and the flat walls of the relative container, tending thus to impede a proper isolation of the bottled product from the surrounding environment.
The object of the present invention is to overcome the problems described above through the adoption of a communicating duct for containers that can both guarantee a fluid-tight seal and ensure there will be no stagnation in the container either of flushing liquids, after the cleansing operation, or of liquid food products when poured for consumption.
A further object of the invention is to simplify the operations by which the communicating duct and the relative container are joined together.